The present invention relates to a gliding board, such as a snowboard, a ski or the like.
A known snowboard or ski has a core structure constructed by bonding fiber-reinforced plastic members reinforced by glass fibers, aramid fibers, carbon fibers or boron fibers, or metal members of a light metal, such as titanium or aluminum, to a core member of a synthetic resin, such as a foam urethane resin, or of composite wood.
A ski disclosed in JP-A No. 52-132936 is constructed by filing alternate upper and lower spaces formed in a corrugated core member waving in variable amplitude according to the thickness distribution of the ski with a synthetic resin, and by bonding a top surface member and a bottom surface member to the core member.
JP-B No. 8-24733 discloses a ski having a fiber-reinforced resin core structure constructed by applying a synthetic resin to a three-dimensional fabric core member which consists of flat fabric plate weavingly attached to a corrugated fabric member having round ridges and round furrows or having walls arranged in successive X-shapes, and discloses a ski having a core structure formed by filling voids in the foregoing fiber-reinforced plastic core structure with a lightweight plastic material, such as a foam urethane resin or a foam epoxy resin.
The known snowboard or ski has a core structure constructed by bonding fiber-reinforced plastic members reinforced by glass fibers, aramid fibers, carbon fibers or boron fibers, or metal members of a light metal, such as titanium or aluminum, to the core member of a synthetic resin, such as a foam urethane resin, or of composite wood and has sufficient longitudinal rigidity and longitudinal strength. However, sufficient consideration is not given to lateral rigidity and lateral strength of the snowboard.
The snowboard has a width twice wider than that of the ski, a relatively thin peripheral part and a relatively thick central part. Therefore sufficient consideration must be given to lateral rigidity and lateral strength of the snowboard to secure stable edge holding performance during curving.
When the snowboard is constructed with a core member made of synthetic resin, such as foam urethane resin, or composite wood, so as to secure sufficient longitudinal rigidity and longitudinal strength, the lateral torsional rigidity of the snowboard becomes very high, and it spoils a contacting performance of the snowboard for maintaining intimate contact with the undulations of the snow surface.
The ski disclosed in JP-A No. 52-132936 has a core structure formed by bonding a top plate and a bottom plate to the upper and the lower edges of the triangular ridges of a core member of a triangular waveform formed by working a plate of a light metal, such as aluminum, or a plastic, such as an ABS resin (acrylonitrile butadiene styrene resin). Therefore, it is difficult to secure a sufficiently large bonding area on the corrugated core member for the top and the bottom plate, and bonding strength bonding together the top plate and the core member and the bottom plate and the core member is insufficient. Therefore, spaces between the top plate and the core member and those between the bottom plate and the core member are filled up with a synthetic resin to secure a sufficient bonding strength, which, however, increases the weight of the ski and makes it difficult to design the ski so that the ski has sufficient rigidity.
The ski disclosed in JP-B No. 8-24733 has a sufficient bonding strength by weavingly attaching the flat fabric plate to the corrugated fabric member. However, application of a synthetic resin to the three-dimensional fabric core member results in the dispersion of the rigidity of the ski, because the synthetic resin can not penetrate enough of thick fabric plate or the thick corrugated fabric. On the contrary, when the fabric plate and the corrugated fabric are made thinner to avoid the dispersion of the rigidity of the ski, the rigidity and/or the strength of the ski become smaller.
The present invention has been made in view of those problems, and it is therefore an object of the present invention to provide a gliding board which has stable edge holding performance and stable gliding performance by having a small torsional/longitudinal bending rigidity ratio and a high lateral bending rigidity, while having a similar longitudinal bending rigidity compared to those of conventional snowboards and skis.
A gliding board in accordance with the present invention has a core structure which consists of a core member of the shape of a rectangular or trapezoidal waveform waving forwardly and rearwardly in the longitudinal direction of the gliding board, a top flat plate and a bottom flat plate bonded to the top surface and the bottom surface of the core member respectively. By this construction, the gliding board has a small torsional/longitudinal bending rigidity ratio and a high lateral bending rigidity while having a similar longitudinal bending rigidity compared to that of the conventional gliding board, which generate stable edge holding performance during curving and stable gliding performance.
Since the core member has laterally extending rectangular or trapezoidal ridges and furrows, a large bonding area is available for bonding both the plates to the surfaces of the core member.
Accordingly, the core member and the plates can easily be bonded together with a high bonding strength.
In the gliding board of the present invention, the heights of the rectangular or trapezoidal ridges and furrows of the core member may be formed depending on the thicknesses of the various parts of the gliding board in the longitudinal direction. And, this characteristic provides a central part of the gliding board on which a large load is exerted with a high rigidity so that the central part may not be bent greatly and can, distribute the load properly on the snow surface. Also, this characteristic provides both longitudinal ends of the gliding board with a bending rigidity and a torsional rigidity lower than those of the central part so that the gliding board is capable of contacting with the undulations of the snow surface.
The fine adjustment of the longitudinal bending rigidity, the torsional rigidity and the lateral bending rigidity of the gliding board of the present invention can be achieved by longitudinally arranging the rectangular or trapezoidal ridges at different pitches.
The fine adjustment of the longitudinal bending rigidity and the torsional rigidity of the gliding board of the present invention can easily be achieved by wrapping a fiber-reinforced plastic member around and bonding the same to the core structure.
The fine adjustment of the longitudinal bending rigidity and torsional rigidity of the gliding board of the present invention can easily be achieved by bonding members of a synthetic resin to the opposite sides of the core structure.